Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K15/00—Anti-oxidant compositions; Compositions inhibiting chemical change
  • C09K15/04—Anti-oxidant compositions; Compositions inhibiting chemical change containing organic compounds
  • C09K15/32—Anti-oxidant compositions; Compositions inhibiting chemical change containing organic compounds containing two or more of boron, silicon, phosphorus, selenium, tellurium or a metal
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/08—Iron or steel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
  • B08B3/04—Cleaning involving contact with liquid
  • B08B3/08—Cleaning involving contact with liquid the liquid having chemical or dissolving effect
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D179/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen, with or without oxygen, or carbon only, not provided for in groups C09D161/00 - C09D177/00
  • C09D179/02—Polyamines
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/08—Anti-corrosive paints
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
  • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
  • C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
  • C23C28/3225—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only with at least one zinc-based layer
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
  • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/08—Iron or steel
  • C23G1/083—Iron or steel solutions containing H3PO4
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/34—Pretreatment of metallic surfaces to be electroplated
  • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel

Definitions

• the present disclosure relates to a composition for washing a pickled steel plate and a method for washing a pickled steel plate using the same, and more particularly, to a composition for washing, used in a pickling process for obtaining a steel plate having excellent surface quality by preventing yellowing caused by reoxidation of the surface of a steel plate after pickling, and a method for washing using the same.
• the present disclosure relates to a steel plate subjected to the washing process described above.
• oxide films are formed on the surface of a hot-rolled steel plate obtained by heat treatment at a high temperature followed by hot rolling, the surface of some cold-rolled steel plates obtained by cold rolling followed by water-cooling in the continuous annealing process, or the surface of a steel plate that has been exposed to the atmosphere over a certain period of time. Since such an oxide film deteriorates post-processing quality, the oxide film is removed in the pickling process.
• the pickling process includes steps of: pickling, for removing an oxide film from a surface of a steel plate with an acid solution; washing, for removing the acid solution remaining on the steel plate during pickling; and drying, for removing water remaining during washing.
• pickling for removing an oxide film from a surface of a steel plate with an acid solution
• washing for removing the acid solution remaining on the steel plate during pickling
• drying for removing water remaining during washing.
• the surface of the steel plate may be reoxidized in the washing and the drying, thus darkening and yellowing the surface of the steel plate.
• high-strength steels are susceptible to yellowing due to reoxidation, because they contain a large amount of strong oxidizing components such as manganese, silicon, aluminum, and magnesium. Thereamong, yellowing occurs more severely on a steel plate containing at least 1.0 wt% of manganese.
• KR 2000-0082171 discloses a technique for preventing corrosion of a hot-rolled steel plate during a washing process by neutralizing the pH of the washing solution using sodium hydroxide.
• KR 2006-0079405 discloses a stain and rust inhibitor for pickling a steel plate containing: 40 to 80 vol% of one or two or more of alkylamine, alkyldiamine, and alkyltetramine; 10 to 50 vol% of tetrahydro-1,4-oxazine as a high temperature stabilizer; and at least 10 vol% of anhydrous citric acid as a solution stabilizer.
• US2002-201705 discloses a technique for immobilizing a surface by treating with a solution of gluconate and polyquaternium compound
• JP2001-319765 discloses a technique for treating a discoloration inhibitor produced by the reaction of carboxylic acid and an alkali agent in a discoloration preventing tank following the pickling, and then removing the discoloration inhibitor in a washing tank.
• compositions for treatment of steel plates are described in US 4,390,465 and CN 104120439 .
• an aspect of the present disclosure is to provide a composition for washing a pickled steel plate, capable of preventing reoxidization of a surface of the steel plate after pickling, thus inhibiting yellowing and thereby obtaining a steel plate having excellent surface quality.
• Another aspect of the present disclosure is to provide a method for washing a pickled steel plate using the composition for washing of the present disclosure.
• the present disclosure is to provide a steel plate treated with an anti-yellowing treatment in a washing stage of the pickling process, to prevent yellowing caused by reoxidation of the surface of the steel plate after pickling.
• the present disclosure provides a composition for washing a pickled steel plate, which may include 6 to 14 wt% of a phosphoric acid ester compound, 6 to 19 wt% of an amine-based compound, 1 to 9 wt% of sodium carbonate, 1 to 9 wt% of ammonium acetate, 1 to 14 wt% of ethylene diamine tetraacetic acid (EDTA) and a remainder of water.
• a composition for washing a pickled steel plate which may include 6 to 14 wt% of a phosphoric acid ester compound, 6 to 19 wt% of an amine-based compound, 1 to 9 wt% of sodium carbonate, 1 to 9 wt% of ammonium acetate, 1 to 14 wt% of ethylene diamine tetraacetic acid (EDTA) and a remainder of water.
• EDTA ethylene diamine tetraacetic acid
• the present disclosure provides a composition for washing a pickled steel plate, which may include 15 to 24 wt% of a phosphoric acid ester compound, 5 to 15 wt% of citric acid, 2 to 10 wt% of sodium carbonate, 2 to 12 wt% of sodium acetate, 1 to 7 wt% of diethylene tetramine pentaacetic acid (DTPA), and a remainder of water.
• a composition for washing a pickled steel plate which may include 15 to 24 wt% of a phosphoric acid ester compound, 5 to 15 wt% of citric acid, 2 to 10 wt% of sodium carbonate, 2 to 12 wt% of sodium acetate, 1 to 7 wt% of diethylene tetramine pentaacetic acid (DTPA), and a remainder of water.
• DTPA diethylene tetramine pentaacetic acid
• the phosphoric acid ester compound is at least one selected from the group consisting of bisphenol A-bis(diphenyl phosphate), triaryl phosphate isopropylate, dimethylmethyl phosphate, tetraphenyl m-phenylene bis(phosphate), triethyl phosphate and triphenyl phosphate.
• the amine-based compound is at least one selected from the group consisting of ethylamine, methylamine, propylamine, butylamine, polyethylamine, polypropylamine, polybutylamine and polyarylamine.
• the composition for washing has a pH of at least 8.0, or in more detail, a pH of 8.5 to 11.5.
• compositions for washing in an amount of 0.05 to 1.5 wt% is diluted with water.
• a method for washing a pickled steel plate may include preparing a composition for washing a pickled steel plate by mixing 6 to 14 wt% of a phosphoric acid ester compound, 6 to 19 wt% of an amine-based compound, 1 to 9 wt% of sodium carbonate, 1 to 9 wt% of ammonium acetate, 1 to 14 wt% of EDTA, and a remainder of water, and diluting the composition for washing with water, and immersing the pickled steel plate in the composition for washing.
• a method for washing which may include preparing a composition for washing a pickled steel plate by mixing 15 to 24 wt% of a phosphoric acid ester compound, 5 to 15 wt% of citric acid, 2 to 10 wt% of sodium carbonate, 2 to 7 wt% of sodium acetate, 1 to 7 wt% of diethylene tetramine pentaacetic acid (DTPA), and a remainder of water, and diluting the composition for washing with water, and immersing the pickled steel plate in the composition for washing.
• DTPA diethylene tetramine pentaacetic acid
• the diluting the composition for washing with water in each of the methods for washing described above is performed by diluting 0.05 to 1.5 wt% of the composition for washing with water.
• the phosphoric acid ester compound is at least one selected from the group consisting of bisphenol A-bis(diphenyl phosphate), triaryl phosphate isopropylate, dimethylmethyl phosphate, tetraphenyl m-phenylene bis(phosphate), triethyl phosphate and triphenyl phosphate.
• the amine-based compound is at least one selected from the group consisting of ethylamine, methylamine, propylamine, butylamine, polyethylamine, polypropylamine, polybutylamine and polyarylamine.
• the composition for washing has a pH of at least 8.0.
• Another aspect of the present disclosure is to provide an anti-yellowing treated steel plate, in which the steel plate contains at least 1.0 wt% of Mn, and also contains a component of 0.01 to 5 mg/m 2 of P, 0.01 to 500 mg/m 2 of C, and 0.1 to 500 mg/m 2 of O other than the steel component on the surface of the steel plate after pickling and washing.
• the steel plate may have a yellowness index of at most 4.0 and a whiteness index of at least 55.
• the surface of the steel plate may contain 0.01 to 5 mg/m 2 of at least one component selected from the group consisting of N, F, Na, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Cl, Zn, Zr and Mo, in addition to the steel components.
• various types of oxide films are formed on the surface of a hot-rolled steel plate obtained by heat treatment at a high temperature followed by hot rolling, the surface of some cold-rolled steel plates obtained by cold rolling followed by water-cooling in the continuous annealing process, or the surface of a steel plate that has been exposed to the atmosphere over a certain period of time. Since such an oxide film deteriorates the post-processing quality, the oxide film is removed in the pickling process.
• the pickling process includes steps of: pickling, for removing an oxide film from a surface of a steel plate with an acid solution; washing, for removing the acid solution remaining on the steel plate during pickling; and drying, for removing water remaining during washing.
• pickling for removing an oxide film from a surface of a steel plate with an acid solution
• washing for removing the acid solution remaining on the steel plate during pickling
• drying for removing water remaining during washing.
• the surface of the steel plate is reoxidized in the washing and the drying, thus darkening the surface of the steel plate.
• high-strength steels contain many strong oxidizing steel components such as manganese, silicon, aluminum, and magnesium, the deterioration of the whiteness index due to reoxidation occurs more severely.
• the present disclosure provides a composition for washing in a pickling process and a method for washing using the same, which are capable of obtaining a steel plate having excellent surface quality by preventing reoxidation and yellowing of the surface of the steel plate after pickling.
• a composition for washing a pickled steel plate comprising a phosphoric acid ester compound, an amine-based compound, sodium carbonate, ammonium acetate, ethylene diamine tetraacetic acid (EDTA) and a remainder of water.
• the composition for washing includes 6 to 14 wt% of a phosphoric acid ester compound, 6 to 19 wt% of an amine-based compound, 1 to 9 wt% of sodium carbonate, 1 to 9 wt% of ammonium acetate, 1 to 14 wt% of EDTA, and a remainder of water.
• the phosphoric acid ester compound may be at least one selected from the group consisting of bisphenol A-bis(diphenyl phosphate), triaryl phosphate isopropylate, dimethylmethyl phosphate, tetraphenyl m-phenylene bis(phosphate), triethyl phosphate and triphenyl phosphate.
• the phosphoric acid ester compound may be contained in an amount of 8 to 12 wt%.
• the amine-based compound may be at least one selected from the group consisting of ethylamine, methylamine, propylamine, butylamine, polyethylamine, polypropylamine, polybutylamine and polyarylamine.
• the amine-based compound may be contained in an amount of 10 to 14 wt%.
• Sodium carbonate is a component used for adjusting the pH of the washing solution composition of the present disclosure, and when sodium carbonate is present in an amount less than 1 wt%, there is a problem in that it is difficult to adjust the pH to a favorable value for preventing yellowing, and when above 9 wt%, there is a problem in that deposits may be generated during washing.
• the sodium carbonate may be contained in an amount of 4 to 8 wt%.
• the ammonium acetate is a component used for adjusting the pH of the washing solution composition of the present disclosure and improving the solution stability, and when the ammonium acetate is present in an amount less than 1 wt%, there is a problem in that deposits may be generated during washing, and when above 9 wt%, there is a problem in that the effect is saturated and malodor may be generated.
• the ammonium acetate may be contained in an amount of 3 to 7 wt%.
• the ethylene diamine tetraacetic acid (EDTA) is a component used for suppressing the yellowing of the washing solution composition of the present disclosure, and when below 1 wt%, there is a problem in that satisfactory yellowing prevention capability may not be exhibited, and when above 14 wt%, there is a problem in that the solution stability is deteriorated.
• the EDTA may be contained in an amount of 6 to 10 wt%.
• the composition for washing a pickled steel plate according to the present disclosure includes a remainder of water. That is, the water is contained in an amount such that the water and the other components of the composition for washing a pickled steel plate of the present disclosure total the total amount of 100 wt%. According to the present disclosure, the water may be purified water.
• a composition for washing a pickled steel plate including a phosphoric acid ester compound, citric acid, sodium carbonate, sodium acetate, DTPA (diethylene tetramine pentaacetic acid) and a remainder of water, in which the composition for washing includes 15 to 24 wt% of a phosphoric acid ester compound, 5 to 15 wt% of citric acid, 2 to 10 wt% of sodium carbonate, 2 to 12 wt% of sodium acetate, 1 to 7 wt% of DTPA, and a remainder of water.
• the composition for washing includes 15 to 24 wt% of a phosphoric acid ester compound, 5 to 15 wt% of citric acid, 2 to 10 wt% of sodium carbonate, 2 to 12 wt% of sodium acetate, 1 to 7 wt% of DTPA, and a remainder of water.
• the phosphoric acid ester compound may be at least one selected from the group consisting of bisphenol A-bis(diphenyl phosphate), triaryl phosphate isopropylate, dimethylmethyl phosphate, tetraphenyl m-phenylene bis(phosphate), triethyl phosphate and triphenyl phosphate.
• the phosphoric acid ester compound may be contained in an amount of 18 to 21 wt%.
• the citric acid is a component that enables enhancement of a whiteness index of high-strength steel, and when less than 5 wt% of phosphoric acid ester compound is added, there is a problem in that satisfactory whiteness index enhancement capability may not be exhibited, and when above 15 wt%, there is a problem in that deposits may be generated during washing.
• the citric acid may be contained in an amount of 9 to 13 wt%.
• the sodium carbonate is a component used for adjusting the pH of the washing solution composition of the present disclosure, and when sodium carbonate is present in an amount less than 2 wt%, there is a problem in that it is difficult to adjust the pH to a favorable value for improving whiteness index, and when above 10 wt%, there is a problem in that deposits may be generated during washing.
• the sodium carbonate may be contained in an amount of 4 to 8 wt%.
• the sodium acetate is a component used for adjusting the pH of the washing solution composition of the present disclosure and improving the solution stability, and when the sodium acetate is present in an amount less than 2 wt%, there is a problem in that deposits may be generated during washing, and when above 12 wt%, there is a problem in that the effect is saturated and stain may be generated on the steel plate.
• the sodium acetate may be contained in an amount of 5 to 9 wt%.
• the diethylene tetramine pentaacetic acid (DTPA) is a component used for improving whiteness index of the washing solution composition of the present disclosure, and when the DTPA is present in an amount less than 1 wt%, there is a problem in that satisfactory whiteness index enhancement capability may not be exhibited, and when above 7 wt%, there is a problem in that the solution stability is deteriorated.
• the DTPA may be contained in an amount of 2 to 4 t wt%.
• the composition for washing a pickled steel plate according to the present disclosure includes a remainder of water. That is, the water is contained in an amount such that the water and the other components of the composition for washing a pickled steel plate of the present disclosure total the total amount of 100 wt%. According to the present disclosure, the water may be purified water.
• each of the compositions for washing a pickled steel plate is adjusted in pH to reduce the corrosion rate of the steel plate, and the composition for washing has a pH of at least 8.0, and in more detail, the composition for washing may have a pH of 8.5 to 11.5.
• the pH of the composition for washing a pickled steel plate of the present disclosure is less than 8.0, there is a problem in that the corrosion rate reduction effect is insufficient and therefore, satisfactory yellowing prevention capability may not be exhibited.
• the composition for washing a pickled steel plate having a pH of at least 8.0 is used, as described in the present disclosure, the steel plate may be washed in regions of weak corrosion or in stable regions so that the yellowing prevention capability may be enhanced.
• composition for washing according to the present disclosure When the composition for washing according to the present disclosure is applied to washing of a pickled steel plate, 0.05 to 1.5 wt% of the composition is diluted with water.
• concentration of the diluted composition for washing is less than 0.05 wt%, there is a problem in that satisfactory yellowing prevention capability may not be exhibited, and when above 1.5 wt%, there is a problem of deteriorated economic feasibility, because adding the composition until after the effect is saturated is economically meaningless.
• the pickled steel plate to which the composition for washing according to the present disclosure may be applied is not particularly limited, although the steel may be a steel plate pickled in any process of pickling steel, such as a hot-rolled pickling process, a hot-rolled pickling oiling process, a hot-rolled pickling plating process, a continuous annealing process, a stainless process, a hot-dip plating process, an electrogalvanizing process, and the like.
• a hot-rolled pickling process such as a hot-rolled pickling process, a hot-rolled pickling oiling process, a hot-rolled pickling plating process, a continuous annealing process, a stainless process, a hot-dip plating process, an electrogalvanizing process, and the like.
• the yellowing of the high-strength steel plate may be suppressed, and therefore, the steel plate having excellent whiteness index may be obtained.
• a method for washing a pickled steel plate according to the present disclosure includes preparing a composition for washing a pickled steel plate, respectively by mixing a phosphoric acid ester compound, an amine-based compound, sodium carbonate, ammonium acetate, ethylene diamine tetraacetic acid (EDTA) and a remainder of water; or by mixing a phosphoric acid ester compound, citric acid, sodium carbonate, sodium acetate, diethylene tetramine pentaacetic acid (DTPA) and a remainder of water; diluting each composition for washing with water; and immersing the pickled steel plate in each composition for washing.
• a phosphoric acid ester compound an amine-based compound, sodium carbonate, ammonium acetate, ethylene diamine tetraacetic acid (EDTA) and a remainder of water
• EDTA ethylene diamine tetraacetic acid
• DTPA diethylene tetramine pentaacetic acid
• each of the components of the composition for washing and content thereof are as described above.
• each composition for washing with water when diluting each composition for washing with water, it is possible to dilute 0.05 to 1.5 wt% of each composition for washing with water.
• concentration of the diluted composition for washing is less than 0.05 wt%, there is a problem in that satisfactory yellowing prevention capability may not be exhibited, and when above 1.5 wt%, there is a problem of deteriorated economic feasibility, because adding the composition until after the effect is saturated is economically meaningless.
• the immersing is performed at room temperature for 1 to 60 seconds, or in more detail, for 5 to 20 seconds, such as for about 10 seconds, for example. Accordingly, using the composition for washing according to the present disclosure enables sufficient washing even for a short time at room temperature and also prevents the yellowing of the steel plate.
• the method for washing according to the present disclosure may further include drying that is not particularly limited.
• drying may be performed by, for example, a hot air drying method, an oven drying method, or the like.
• the steel plate washed with the composition for washing described above may suppress the yellowing of the surface.
• the high-strength steel containing a large amount of Mn may be washed using each composition described above to further improve the anti-yellowing effect. Particularly effective result is expected when the composition is applied to the high-strength steel plate including Mn. It is possible to apply the composition to a steel plate that contains at least 1.0 wt% of Mn among the steel components of the steel plate.
• the steel plate containing less than 1.0 wt% of Mn has anti-yellowing capability after pickling and does not suffer severe yellowing. Therefore, such a steel plate, which is not susceptible to yellowing, is not necessarily subjected to a separate anti-yellowing treatment. Meanwhile, a steel plate containing at least 1.0 wt% of Mn has yellowing after pickling, and in this case, the steel plate with yellowing needs to be subjected to an anti-yellowing treatment, because it will deteriorate the quality, such as phosphate processability, Ni flash treatment ability, paintability or the like in the subsequent process after the pickling.
• the steel plate subjected to the anti-yellowing treatment using the composition for washing provided according to the present disclosure contains P, C, and O as components other than the steel components on the surface of the steel plate.
• P and C are residues of the oxidation inhibiting components of the composition for washing which remain on the surface of the steel plate after drying in the process of washing after pickling of the steel plate.
• O is an element detected from the oxidation inhibiting components contained in the washing solution and the oxide component inevitably formed on the surface of the steel plate during the washing process after pickling.
• the steel plate When P, C, and O are attached to the surface of the steel plate after washing by a predetermined amount, the steel plate is inhibited from being reoxidized in the process of washing and drying after washing.
• 0.01 to 5 mg/m 2 of P is attached to the surface of the pickled and washed, anti-yellowing treated steel plate of the present disclosure.
• the coating amount of P is less than 0.01 mg/m 2 , sufficient anti-yellowing effect may not be exhibited, and when the coating amount of P is greater than 5 mg/m 2 , there is a problem in that stain occurs on the steel plate and the surface is rather darkened.
• the anti-yellowing treated steel plate of the present disclosure has not only P, but also 0.01 to 500 mg/m 2 of C attached to the surface of the steel plate.
• the coating amount of C is less than 0.01 mg/m 2 , there is a problem in that sufficient anti-yellowing may not be exhibited, and when the coating amount of C is more than 500 mg/m 2 , there is a problem in that the surface appearance degrades and the phosphate processability also deteriorates in the subsequent process.
• the anti-yellowing treated steel plate of the present disclosure contains O as well as P and C, and in more detail, 0.1 to 500 mg/m 2 of O are attached.
• the coating amount of O is less than 0.1 mg/m 2 , there is a problem in that sufficient anti-yellowing may not be exhibited, and when above 500 mg/m 2 , there is a problem in that severe yellowing causes a poor surface appearance, and also the deteriorated phosphate processability in the post-processing.
• the anti-yellowing treated steel plate of the present disclosure may further contain N, F, Na, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Cl, Zn, Zr, Mo as well as P, C, and O, in addition to the steel component on the surface of the steel plate.
• These components may contain one, or two or more components.
• the components mentioned above may be present such that a total coating amount thereof is 0.01 to 5 mg/m 2 .
• the total coating amount of the additional components described above is less than 0.01 mg/m 2 , the effect of suppressing the occurrence of minute stains on the surface is insignificant, and when the coating amount is above 5 mg/m 2 , there is a problem in that it rather causes increased occurrence of stains and deteriorated surface appearance.
• the anti-yellowing treated steel plate according to an embodiment of the present disclosure may suppress the yellowing of the pickled and washed steel plate as a predetermined amount of P, C, and O are attached to the surface of the pickled and washed steel plate as described above.
• the quality of the anti-yellowing treated steel plate may be represented by the yellowness index and whiteness index measured by a colorimeter (Minolta Spectrophotometer, CM3700d), and in some embodiments, the yellowness index of the steel plate surface is less than 4.0 and the whiteness index is at least 55.
• the lower yellowness index of the surface of the steel plate which does not exceed 4.0, results in improved surface appearance, and when the yellowness index exceeds 4.0, there is a problem in that the surface appearance is poor and the phosphate processability is deteriorated in post-processing.
• the surface whiteness index of the anti-yellowing treated steel plate may be at least 55.
• the higher whiteness index, which is no less than 55 results in more enhanced anti-yellowness and superior surface appearance, and when the whiteness index is less than 55, there is a problem in that the surface appearance is poor and the phosphate processability in a post-processing is deteriorated.
• the anti-yellowing treated steel plate according to one embodiment of the present disclosure may effectively suppress the occurrence of yellowing due to reoxidation of the steel plate after pickling, washing, and drying, and may be produced in any process of pickling the steel plate, such as a subsequent hot-rolled pickling process, a hot-rolled pickling inunction process, a hot-rolled pickling plating process, a continuous annealing process, a stainless process, a hot-dip plating process, an electrogalvanizing process, and the like.
• the anti-yellowing treated steel plate may be produced by applying an oxidation inhibitor composition capable of providing P, C, and O on the surface of the steel plate in the coating amount mentioned above to wash the pickled steel plate and drying the same.
• the oxidation inhibitor composition is not particularly limited as long as it contains components that are capable of attaching P, C, and O to the surface of the steel plate, for example.
• An example of the oxidation inhibitor composition includes a phosphoric acid ester compound, an amine-based compound, carbonate compound, a glycol compound, an acetate compound, and the like.
• the oxidation inhibitor composition as described above may be added to any of the washing solutions for washing the pickled steel plate such that by the washing process of the pickled steel plate and drying, the anti-yellowing treated steel plate may be prepared. At this time, the P, C, and O are left remaining on the surface of the steel plate by a predetermined amount as described, and accordingly, the anti-yellowing treated steel plate provided in the present disclosure may be obtained.
• the contents of P, C, and O attached to the surface of the steel plate may be obtained by appropriately adjusting the composition of the pickling solution or washing solution. In addition, it may be obtained by adjusting the intervals between washing processes after pickling, or adjusting the time for washing.
• the method is not particularly limited as long as P, C, and O may be attached in the amount described above.
• a material for pickling was prepared by machining a 980 MPa grade hot-rolled steel plate having a thickness of 1.2 mm, and 2.8 w% of manganese and 1.1 w% of silicon into a size of 100 ⁇ 100 mm 2 (W/L), and then immersed and pickled in 500 ml of 15 wt% of hydrochloric acid at 80 °C for 30 seconds.
• the resulting pickled steel plate was immersed in 500 ml of distilled water at room temperature for 10 seconds, to which 0.5 w% of the composition for washing according to the present disclosure was added.
• composition for washing used herein was prepared with the components and in the contents shown in Table 1 below to obtain a final composition for washing.
• Table 1 below water is included in the remaining amount, based on 100 w%.
• the yellowing prevention capability was evaluated based on the following criteria by measuring a yellowness index of the specimen after the pickling with the colorimeter (Minolta Spectrophotometer, CM3700d).
• solution stability was evaluated based on the following criteria using a method of storing the crude liquid of the composition for washing in a thermostatic bath at 50 °C for 3 days, measuring the change in viscosity before and after storage, and observing whether sludge was generated, and a method of adding 0.5 wt% of the composition for washing to distilled water, washing the pickled specimen with water, and then observing whether deposit or floating matters occurred.
• Viscosity change is within 20%, no sludge and deposit/floating matter occur
• X Viscosity change exceeds 20%, or sludge or deposit/floating matter occur
• the pickled composition according to the present disclosure has excellent yellowing prevention capability and solution stability and shows excellent properties without any problems.
• composition for washing was diluted with water to use, in which case the same pickling and washing as described in Experimental Example 1 were carried out, while varying the pH and the addition amount of composition for washing, and the yellowing prevention capability of the resulting specimen was evaluated in the same manner as described in Experimental Example 1 and the results are shown in Table 2.
• a material for pickling was prepared by machining a 980 DP hot-rolled steel plate having a thickness of 1.2 mm, and 2.8 w% manganese and 1.1 w% silicon into a size of 100 ⁇ 100 mm2 (W/L), and then immersed and pickled in 500 ml of 15 wt% of hydrochloric acid at 80 °C for 30 seconds.
• the resulting pickled steel plate was immersed in 500 ml of distilled water at room temperature for 10 seconds, to which 0.5 w% of the composition for washing according to the present disclosure was added.
• composition for washing used herein was prepared with the components and in the contents shown in Table 3 below to obtain a final composition for washing.
• water is included by the remaining amount based on 100 w%.
• the whiteness index enhancement capability was evaluated based on the following criteria, by measuring a whiteness index of the specimen after the pickling with the colorimeter (Minolta Spectrophotometer, CM3700d).
• the pickled composition according to the present disclosure has excellent whiteness enhancement capability and solution stability and shows excellent properties without any problems.
• a specimen that was 100 mm x 100 mm in width and length was prepared by machining a 980 MPa grade hot-rolled steel plate having a thickness of 1.2 mm and containing 1.1 w% of Si and Mn content as shown in Table 5 below.
• the yellowness index and whiteness index of each specimen after pickling and washing were measured using a colorimeter (Minolta Spectrophotometer, CM3700d) and the yellowing prevention capability was evaluated according to the occurrence of yellowing. The evaluation was carried out according to the following criteria.
• each of the pickled and washed specimens was subjected to surface conditioning and phosphate treating under the following conditions.
• the coating amount of phosphate to each of the phosphate-treated specimens was measured according to the wet process, and the phosphate processability was evaluated based on the coating amount. At this time, evaluation of the phosphate processability was performed according to the following criteria. ⁇ - Good phosphate processability: coating amount is at least 1.0 g/m 2 ⁇ - Poor phosphate processability: coating amount is less than 1.0 g/m 2
• specimen 1 containing less than 1.0 wt% of manganese in the steel composition showed no yellowing, and accordingly, the results indicated that specimen 1 had yellowing prevention capability, and phosphate processability was also indicated to be excellent.
• the steel containing at least 1.0 wt% of manganese needs to be provided with yellowing prevention capability by the yellowing treatment.
• the pickling process was carried out under the same conditions as described above in Reference Example 3 using the same specimen 3 as that used in Reference Example 3 that contains 2.8 wt% of Mn.
• the pickled specimen was immersed in 500 ml of washing solution for 10 seconds to be washed.
• the base washing solution was prepared by adding 0.5 wt% of an oxidation inhibitor composed of 15 wt% of phosphoric acid ester, 12 wt% of ethylamine, 6 wt% of sodium carbonate, 5 wt% of ammonium acetate, 6 wt% of EDTA, and a remainder of water, to the distilled water.
• the yellowness index of the specimens washed with each washing solution was measured to confirm whether the specimens had the yellowing prevention capability.
• the surface appearance properties were evaluated by visually observing the surfaces of the specimens after the washing and the specimens after phosphate treatment in each of the Experimental Examples and the Comparative Examples for presence of stains on the surfaces, and the surface appearance properties were evaluated based on the following criteria.
• ⁇ - Good surface appearance No stains
• ⁇ - Medium surface appearance Minute stains, but acceptable for sale
• ⁇ - Poor surface appearance Severe stains
• P C O N+S+Na yellowing prevention capability phosphate treatment property surface appearance Comp. Ex. 1 0.005 1.1 2 0 ⁇ ⁇ ⁇ Ex. 1 0.01 1.1 2 0 ⁇ ⁇ ⁇ Ex.
• the surfaces of the specimens having yellowing prevention capability after pickling and washing contained P in a range of 0.01 to 5 mg/m 2 , C in a range of 0.01 to 500 mg/m 2 , and O in a range of 0.01 to 500 mg/m 2 .
• specimens having the yellowing prevention capability also showed excellent phosphate processabilities, along with good surface appearance properties.
• the coating amount of P is less than 0.01 mg/m 2 (Comparative Example 1), or the coating amount of C is less than 0.01 mg/m 2 (Comparative Example 3), or the coating amount of O is less than 0.1 mg/m 2 (Comparative Example 5), the measured yellowness index exceeded 4, and the measured whiteness index was less than 55, which showed poor yellowing prevention capability.
• the coating amount of the phosphate was less than 1.0 g/m 2 , indicating that phosphate treatment property was also poor.
• N, S, and Na were additionally attached to the surface of the specimen after pickling and washing, in addition to the P, C, and O contents being attached according to the ranges of the present disclosure.
• Example 10 the total coating amount of N+Na+S was 0.005 mg/m 2 , which was less than 0.1 mg/m 2 , and therefore, no further improvement of the surface appearance properties was obtained. However, in Examples 11 to 13 having at least 0.1 mg/m 2 of total coating amount of N+Na+S, the results showed that both phosphate processability and surface appearance were excellent.
• N, S, and Na may be attached to the surface of the pickled and washed steel plate, the content thereof may be in the range of 0.2 to 5 mg/m 2 to ensure that intended result is obtained.

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